Shift Register Gate Driving Circuit for Leakage-Free Pull-Up
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Solution Overview
Problem
Current gate driving circuits suffer from current leakage due to improper circuit design, which prevents the gate signal from being pulled up to a target voltage level, affecting the proper functioning of the circuit.
Innovation Solution
The proposed gate driving circuit incorporates plural-stage shift registers with a pull-up unit, energy-store unit, start-up unit, discharging units, and leakage-preventing units to manage voltage levels and prevent current leakage by controlling the discharging and pulling down of signals when the gate signal reaches a high voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple shift register design is used, then the device complexity is low, but current leakage occurs and the gate signal cannot be pulled up to the target voltage level
Solution Approach 1:
The shift register circuit is segmented into multiple functional units: pull-up unit (transistors T21, T22), energy-store unit (capacitor C), start-up unit (transistor T11), discharging unit (transistor T42), and leakage-preventing unit (transistors T47, T48). Each unit performs a specific function to collectively solve the current leakage problem while maintaining manageable complexity through modular design.
Solution Approach 2:
The energy-store unit (capacitor C) performs preliminary charging to store driving voltage before the pull-up operation. The start-up unit activates the charging process in advance, ensuring that sufficient voltage is available when the pull-up unit needs to operate, preventing voltage droop and current leakage.
Solution Approach 3:
The leakage-preventing unit converts the potentially harmful current leakage through the discharging unit into a beneficial control mechanism. By detecting the gate signal voltage level and controlling the discharging unit's operation, the circuit uses the leakage path as a feedback signal to regulate the energy-store unit's charging and discharging cycles, ensuring stable voltage levels.
2Speed
If the discharging unit remains active continuously, then the energy-store unit can be quickly discharged when needed, but current leakage prevents the gate signal from reaching the high voltage level
Solution Approach 1:
The discharging unit's operation is made dynamic rather than static. The transistor T42 is controlled to switch between on and off states based on real-time voltage level detection. When the gate signal reaches the target high voltage level, the leakage-preventing unit (T47, T48) turns off T42, stopping the discharging action. This dynamic control allows fast discharging when needed while preventing continuous discharge that would cause voltage droop.
Solution Approach 2:
The leakage-preventing unit implements a feedback mechanism where transistors T47 and T48 continuously monitor the gate signal voltage level and the driving voltage from the energy-store unit. Based on this feedback, they control the discharging unit T42 to operate only when appropriate, ensuring the gate signal reaches and maintains the required high voltage level without excessive discharge.
Data Source
AI summary
A shift register of a gate driving circuit includes a pull-up unit for pulling up a first output signal and a first gate signal to a high voltage level according to a driving voltage and a high-frequency clock signal, a start-up unit for transmitting a second gate signal, an energy-store unit for providing the driving voltage to the pull-up unit according to the second gate signal, a first discharging unit for pulling down the driving voltage to a first voltage level according to a first control signal, a first leakage-preventing unit for turning off the first discharging unit when the first gate signal reaches the high voltage level, a first pull-down unit for respectively pulling down the first output and first gate signals to the first and a second voltage levels according to the first control signal, and a first control unit for generating the first control signal.